Laminated guitar neck and process for manufacture thereof

ABSTRACT

A number of thin sheets of wood are arranged alternately with dry sheets of paper impregnated with a thermosetting resin as an adhesive and are pressed together at an elevated temperature. The thus-formed composite structure is secured to a fingerboard in such a manner that its constituent sheets of wood extend generally perpendicular to the plane of the fingerboard. The guitar neck will have an increased rigidity against transverse stresses that may be caused with changes in ambient humidity or in moisture content.

United States Patent [191 Okugawa v LAMINATED GUITAR NECK AND PROCESS FOR MANUFACTURE THEREOF [75] Inventor: Toshimune Okugawa, Hamamatsu,

Japan [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsu-shi, Japan [22] Filed: Oct. 2, 1972 [2]] Appl. No.: 294,175

[30] Foreign Application Priority Data Oct. 6, 197] Japan 46-92216 52' us. Cl. 84/293 [51] Int. Cl. Gl0d 3/00 [58] Field of Search 84/291, 293

[56] References Cited UNITED STATES PATENTS 3,721,147 3/1973 Okugawa et al. 84/186 WP [111 3,805,663 [.451 Apr. 23, 1974 Primary Examiner-Lawrence R. Franklin Attorney, Agent, or Firm-Kenneth S. Goldfarb [5 7] ABSTRACT A number of thin sheets of wood are arranged alternately with dry sheets of paper impregnated with a thermosetting resin as an adhesive and are pressed together at an elevated temperature. The thus-formed composite structure is secured to a fingerboard in such a manner that its constituent sheets of wood extend generally perpendicular to the plane .of the fingerboard. The guitar neck will have an increased rigidity against transverse stresses that may be caused with changes in ambient humidity or in moisture content.

3 Claims, 5 Drawing Figures RATENTEDAPR 23 1914 3,805,663

FIG.2 F193 11 11 VIII/11171111;

llllllllllllllllll i This invention relates generally to musical instruments, and more specifically to an improved construction of a guitar neck and to a process for the manufacture thereof.

The neck of a guitar has mostly been made either of solid wood or of two or three separate layers of wood glued or otherwise secured together. There has also been known a guitar neck made of solid wood and an elongate bar of metal embedded lengthwise therein with a view to the increase in rigidity. In all these prior art guitar necks, however, the solid wood in use is subject to warpage with the changes in ambient humidity or in moisture content, resulting in the curving of the entire guitar neck in such a manner that the tension of the strings extending therealong is either increased or decreased. This gives rise to the deviations in the spacing between the strings and the frets on the fingerboard and thus hampers correct musical performance by the instrument. Worst yet, the guitar may go entirely out of tune as a consequence of the varied tension of the strings.

Accordingly, it is an object of the present invention to provide a novel and improved guitar neck having increased resistivity to warpage.

Another object of the invention is to provide a guitar neck composed of a number of extremely thin sheets of wood united together so as to reduce transverse strains that may be caused with changes in ambient humidity or in moisture content. I

A further object of the invention is to provide a guitar neck in which the extremely thin sheets of wood are, bonded together by use of what are known in the art as pre-preg sheets or dry sheets of paper impregnated with a thermosetting resin, so that the intrusion of moisture into the sheets of wood during the bonding operation is minimized. Moreover, the interleaving layers of the thermosetting resin present in the completed product function as enclosures for its constituent sheets of wood, preventing the same from moisture intrusion after the bondingoperation.

A further object of the invention is to provide a guitar neck in which the sheets of wood are arrangedperpendicular to the plane of a fingerboard to withstand the pull of the strings.

lt is also an object of the present invention to provide a novel process for the manufacture of a guitar neck in which a number of extremely thin sheets of wood are arranged alternately with the pre-preg sheets and are pressed together at an elevated temperatureto cause adhesion thereof by the pre-preg sheets, thereby reducing the moisture content of the sheets of wood to an extent unattained by the usual glueing operation and further minimizing the transfer of moisture between the adjoining ones thereof.

With these objects in view and the other various ancillary objects and advantages of the present invention hereinafter set forth, the invention will now be described more specifically in conjunction with the accompanying drawings wherein like reference numerals designate like parts throughout the several views, and in which:

FIG. 1 is a side elevational view of a guitar to which are applicable the concepts of the present invention;

FIG. 2 is an enlarged cross sectional view of a guitar neck constructed in accordance with the invention;

FIG. 3 is a fragmentary cross sectional view showing the guitar neck of FIG. 2 on a still more enlarged scale;

FIG. 4 is a view similar to FlG. 3 showing another preferred embodiment of the invention; and

FIG. 5 is a graphic representation for comparison of the warpage of the guitar neck according to the invention with that of the prior art guitar neck as caused under the same environmental conditions.

With particular reference to F IG. 1, in which there is shown the general makeup of-a well known guitar, a neck 10 has a fingerboard ll thereon which is fretted as at 12. A head or pegbox 13 is formed at one end of the neck 10, whereas a shoe or base 14 is formed at the other end to be glued or otherwise secured to a wide, relatively flat body or sound box 15 of waisted outline having a table or soundboard l6 thereon. A plurality of, usually six, strings 17 extend between a string holder 18 affixed to the soundboard 16 and their respective pegs set into the pegbox 13 in a known manner. Bridges are positioned as at 20 and 21 to raise the strings 17 a short distance from the frets l2 and so forth and thus to permit transmission of their vibrations to the sound box 15.

According to the present invention, as best shown in FIG. 2, the neck 10 of the above constructed guitar is composed essentially of a number of veneers or thin sheets 22 of wood each having a thickness in the range of from about 0.5 to' 3.0 millimeters for the best results. These extremely thin sheets of wood may be produced, for example, from the various species of trees generally known as mahogany, and by meansfamiliar to the spe cialists.

For manufacture, the thin sheets of wood 22 are bonded together by use of the commercially available pre-preg sheets or extremely thin sheets of paper impregnated witha thermosetting resin. Such pre-preg sheets may be prepared by' first cutting overlay paper having a thickness of about micromillimeters and a weight of from about 36 to 40 grams per square meter into sheets of proper size, impregnating the sheets of paper with a suitable solution of athermosetting phenolic resin (such for example as that produced and distributed under the trade name Sumilite Resin PR50338 by Sumitomo Bakelite Co., Ltd., of J apan),

and thereafter drying the resin-impregnated sheets of paper by allowing the same to stand for a period of from about 5 to 7 minutes at a temperature of from about 60 to 80 C. The thermosetting phenolic resin lie, the Sumilite Resin PR50338) thus carried by the sheets of paper will usually weigh from about 260 to 290 grams per square meter upon drying.

The dry pre-preg sheets thus prepared and the thin sheets of wood 22 are interlaminated and are pressed together at a temperature of from about to C for a period of from about 70 to 90 minutes. The pressure exerted for this bonding operation may be about 15 kilograms per square centimter.

The neck 10 thus manufactured is glued or otherwise secured to the fingerboard 11 in a manner well known to those in the art. However, as seen in FIGS. 2 and 3, it must be noted that the laminated sheets of wood 22, with the interleaving layers 23 of the thermosetting resin, are arranged perpendicular to the plane of the fingerboard 11 so that the complete neck structure will have an increased rigidity or strength in the direction of the arrow X in FIG. 1 to resist the forces tending to I bend the same in the direction of the arrow Y Alternatively, it is also possible according to this invention to arrange the similarly laminated sheets of wood 22 parallel to the plane of the fingerboard 11 as illustrated in FIG. 4. The bending strength of the neck structure thus constructed is also confirmed to be satisfactory.

Graphically represented in FIG. are the results of bending tests conducted on the guitar neck constructed according to the concepts of this invention and on a prior art guitar neck made of solid wood. The straight or unbent condition of any guitar neck is obtainable at a temperature of about C and a humidity of about 60 per cent. The profiles I and I represent the degrees of warpage exhibited by the guitar neck according to the invention when the ambient humidity was increased and decreased, respectively, to a definite extent from the above noted reference value, whereas the profiles [I and ll represent the corresponding degrees of warpage exhibited by the prior art guitar neck under the same conditions. It may be seen that the warpage of the guitar neck according to this invention with the changes in' ambient humidity is less than half of the warpage suffered correspondingly by the prior art guitar neck.

This is partly because the dry pre-preg sheets used as an adhesive prevent the intrusion of moisture into the sheets of wood 22 during the bonding operation thereof, and partly because the layers 23 of the thermosetting resin existing between the sheets of wood 22 in the completed guitar neck substantially completely enclose each sheet of wood, thereby protecting the same against the influences of the ambient humidity and also preventing the transfer of moisture between the adjoining sheets of wood. It is also noteworthy that the layers 23 interlaminated between the sheets of wood 22 function as a kind of reinforcement to increase the rigidity or strength of the guitar neck according to the invention. The arrangement of the sheets of wood 22 perpendicular to the plane of the fingerboard 11, in particular, is also conductive to the increased bending strength of the entire neck structure.

Although the present invention has been shown and described hereinbefore in very specific aspects thereof, it will be easy for those in the art to make many modifications, substitutions and changes. The invention, therefore, is not intended to be restricted by the exact showing of the drawings and the description thereof but is considered to include other examples coming within the spirit and scope of the invention as defined by the terms of the claims which follow.

What is claimed is:

I. A guitar neck comprising a fingerboard, a plurality of thin sheets of wood ranging from 0.5 to about 3.0 millimeters, means bonding said sheets together, said means including extremely thin dry sheets of paper impregnated with a thermosetting resin, said sheets of wood being secured to said fingerboard.

2. A guitar neck according to claim 1, in which said sheets of wood are arranged perpendicular to the plane of said fingerboard.

3. A guitar neck according to claim 1, in which said sheets of wood are arranged parallel to the plane of said fingerboard. 

1. A guitar neck comprising a fingerboard, a plurality of thin sheets of wood ranging from 0.5 to about 3.0 millimeters, means bonding said sheets together, said means including extremely thin dry sheets of paper impregnated with a thermosetting resin, said sheets of wood being secured to said fingerboard.
 2. A guitar neck according to claim 1, in which said sheets of wood are arranged perpendicular to the plane of said fingerboard.
 3. A guitar neck according to claim 1, in which said sheets of wood are arranged parallel to the plane of said fingerboard. 